Current control in a power distribution unit using a contactor

Abstract

A system including a vehicle having a motive electrical power path, and a power distribution unit having a current protection circuit disposed in the motive electrical power path. The current protection circuit includes a first leg of the current protection circuit comprising a thermal fuse, a second leg of the current protection circuit comprising a contactor. The first leg and the second leg may be coupled in a parallel arrangement. The system further has a controller that includes a current detection circuit structured to determine a current flow through the motive electrical power path, and a fuse management circuit structured to provide a contactor activation command in response to the current flow. The contactor may be responsive to the contactor activation command.

What is claimed is: 
     
       1. A system, comprising:
 a vehicle having a motive electrical power path; 
 a power distribution unit having a current protection circuit disposed in the motive electrical power path, the current protection circuit comprising:
 a first leg of the current protection circuit comprising a thermal fuse; 
 a second leg of the current protection circuit comprising a contactor; and wherein the first leg and the second leg are coupled in a parallel arrangement; 
 a controller, comprising: 
 a current detection circuit structured to determine a current flow through the motive electrical power path; and 
 a fuse management circuit structured to provide a contactor activation command in response to the current flow; and 
 wherein the contactor is responsive to the contactor activation command, and wherein the contactor is open during nominal operations of the vehicle, and wherein the fuse management circuit is structured to provide the contactor activation command as a contactor closing command in response to determining that the current flow is above a thermal wear current for the thermal fuse. 
 
 
     
     
       2. The system of  claim 1 , wherein the thermal fuse comprises a current rating that is higher than a current corresponding to a maximum power throughput of the motive electrical power path. 
     
     
       3. The system of  claim 1 , wherein the thermal fuse comprises a current rating that is higher than a current corresponding to a quick charging power throughput of the motive electrical power path. 
     
     
       4. The system of  claim 1 , wherein the contactor comprises a current rating that is higher than a current corresponding to a maximum power throughput of the motive electrical power path. 
     
     
       5. The system of  claim 1 , wherein the contactor comprises a current rating that is higher than a current corresponding to a quick charging power throughput of the motive electrical power path. 
     
     
       6. The system of  claim 1 , wherein the fuse management circuit is further structured to provide the contactor activation command as a contactor opening command in response to the current flow indicating a motive electrical power path protection event. 
     
     
       7. The system of  claim 6 , wherein the current detection circuit is further structured to determine the motive electrical power path protection event by performing at least one operation selected from the operations consisting of: responding to a rate of change of the current flow; responding to a comparison of the current flow to a threshold value; responding to one of an integrated or accumulated value of the current flow; and responding to one of an expected or a predicted value of any of the foregoing. 
     
     
       8. The system of  claim 1 , wherein the fuse management circuit is further structured to provide the contactor activation command as the contactor closing command in response to determining that the current flow is below a current protection value for the motive electrical power path. 
     
     
       9. The system of  claim 1 , the second leg further comprising a second thermal fuse in series arrangement with the contactor, the thermal fuse having a current threshold value greater than a second current threshold value of the second thermal fuse. 
     
     
       10. The system of  claim 9 , wherein the fuse management circuit is further structured to provide the contactor activation command as a contactor opening command to increase an overall current threshold value of the motive electrical power path. 
     
     
       11. The system of  claim 9 , wherein the fuse management circuit is further structured to provide the contactor activation command as a contactor closing command to provide a sharing of current load between the thermal fuse in the first leg and the second thermal fuse in the second leg. 
     
     
       12. A controller, comprising:
 a current protection circuit disposed in a motive electrical power path, the current protection circuit comprising a thermal fuse and a contactor arranged in parallel; 
 a current detection circuit structured to determine a current flow through the motive electrical power path; and 
 a fuse management circuit structured to provide contactor activation command in response to the current flow; 
 wherein the contactor is responsive to the contactor activation command, and wherein the contactor is open during nominal operations, and wherein the fuse management circuit is structured to provide the contactor activation command as a contactor closing command in response to determining that the current flow is above a thermal wear current for the thermal fuse. 
 
     
     
       13. The controller of  claim 12 , wherein the thermal fuse comprises a current rating that is higher than a current corresponding to a maximum power throughput of the motive electrical power path. 
     
     
       14. The controller of  claim 12 , wherein the thermal fuse comprises a current rating that is higher than a current corresponding to a quick charging power throughput of the motive electrical power path. 
     
     
       15. The controller of  claim 12 , wherein the contactor comprises a current rating that is higher than a current corresponding to a maximum power throughput of the motive electrical power path. 
     
     
       16. The controller of  claim 12 , wherein the contactor comprises a current rating that is higher than a current corresponding to a quick charging power throughput of the motive electrical power path. 
     
     
       17. The controller of  claim 12 , wherein the fuse management circuit is further structured to provide the contactor activation command as a contactor opening command in response to the current flow indicating a motive electrical power path protection event. 
     
     
       18. The controller of  claim 12 , further comprising a second thermal fuse in series arrangement with the contactor, the thermal fuse having a current threshold value greater than a second current threshold value of the second thermal fuse. 
     
     
       19. A method, comprising:
 powering a motive electrical power path of a vehicle through a current protection circuit including a thermal fuse and a contactor arranged in parallel; 
 detecting a current flow through the motive electrical power path; 
 transmitting the detected current flow to a power diagnostic application; 
 determining whether the detected current flow is above a thermal wear current for the thermal fuse; and 
 in response to determining that the detected current flow is above the thermal wear current for the thermal fuse, providing, from the fuse management circuit, a contactor closing command. 
 
     
     
       20. The method of  claim 19 , further comprising providing the thermal fuse having a current rating that is higher than a current corresponding to a maximum power throughput of the motive electrical power path. 
     
     
       21. The method of  claim 19 , further comprising providing the thermal fuse having a current rating that is higher than a current corresponding to a quick charging power throughput of the motive electrical power path. 
     
     
       22. The method of  claim 19 , further comprising providing the contactor having a current rating that is higher than a current corresponding to a maximum power throughput of the motive electrical power path.